Elastan filaments with a titre of at least 2,500 dtex according to the wet spinning method were disclosed for the first time in laid-open print DE 198 290 63 A1. Coarse titres of this kind, which are present in tape form with tape widths of typically approx. 2 to 10 mm and are found in the typical application areas of natural rubber threads, are very attractive economically. Areas of use are, for example, elastic undertapes for upholstery fabrics, base material for underwear, leg borders for lingerie and bathing articles, and special hygiene articles in the medical sector.
In the production of elastan filaments by the dry, wet or melt spinning method, the filaments are as a rule wound on spools. Compare e.g. Ullmann: Encyclopedia of Industrial Chemistry, Vol. A 10; p. 613, FIGS. 15 and 17, VCH Verlagsgesellschaft, Weinheim; 1987.
Depending on the titre, spools with various tube widths, e.g. of approx. 58 to 160 mm, are used. In addition, spools with various weights of elastan filaments are produced.
Tube width and spool weights are naturally governed by the titres of the elastan filaments spun. In order to obtain the highest possible filament line lengths and hence the fewest possible interruptions in the processing of the elastan filaments, elastan filaments for example of 1,280 dtex are produced on wide tubes of 160 mm length with weights of up to approx. 1.5 kg. This corresponds to a filament line length of approx. 11.7 km.
With still coarser titres above 2,500 dtex, correspondingly less line length is achieved on tubes of 160 mm length and 1.5 kg spool weight. Thus for a coarse titre of 10,000 dtex, for example, the filament line length amounts to only 1.5 km under the conditions given above.
Spools of this kind can no longer be used economically due to their short line lengths.
With a production speed of 100 m/min, for example, the spool running time in fact amounts to only 15 minutes in the above case. This means high staff levels for the spool change, which in turn leads to economic disadvantages in the application of spools.
Even if the spool weights are increased, for example to 3 kg, the filament line length continues to be completely unsatisfactory. Furthermore, said heavy spools are more difficult to handle, to transport and to pack by the staff.
The object of the present invention was to correct these serious drawbacks and to provide a store for coarse-titre elastan filaments of more than 2,500 dtex with sufficiently large line length of at least 10 kin, preferably 15 km and in particular of more than 20 km.
It was found that this object can be achieved by using instead of the otherwise conventional winding devices for spools a displacing device with draw-in mechanism and inlaying device for the storing in drums, and by storing the coarse elastan filaments with a titre of more than 2,500 dtex in cartons, instead of winding them on spools.
The invention provides a method for storing elastan filaments with a titre of at least 2,500 dtex in drums with a filament line length of at least 10 kin, preferably at least 15 kin, particularly preferably at least 20 kin, with the use of a displacing device, wherein the filaments are stored meandering in layers, characterised in that the filaments are inlaid into the drum at a speed of at least 8%, preferably at least 10% above the production speed of the filaments. Because the storing meanders, i.e. runs to and fro in the drum, the space in the drum is particularly well utilised.
Preferably a draw-in roller which comprises a teflon coating (PTFE) or a paper jacketing is used to produce the inlaying into the drum.
Particularly preferably a pivoted, funnel-shaped inlayer is used for the storing, whose width at its bottom end, viewed at right angles to the pivoting direction, amounts to not more than 100 mm.
The filaments running into the inlayer are preferably blown on with compressed air in the running direction of the filaments.
This serves to prevent wraps in the area of the storing.
The stored filaments are preferably additionally compressed in the drum, in particular with the use of several press rams, in order to ensure a higher packing density.
The drum is particularly preferably caused to oscillate transversely to the filament running direction and at right angles to the pivoting direction of the inlayer during the storing of the filaments, in order to make optimum use of the space in the drum.
In order to store the elastan filaments as smoothly as possible, the additional transverse oscillating of the carton has proved to be particularly effective. In addition, a uniform filling of the carton is also obtained particularly in the corners if so-called tape holding-down devices, which may be operated alternately, are used as press rams.
Tape displacing devices for the storing of filaments are known in principle.
It was found that coarse elastan filaments of 2,500 dtex and more cannot be processed automatically on the known displacing devices. Filament pile-ups and lapping arise in all cases, because of adhesion proneness and speed differences due to the elastic material, which may exhibit up to 700% extension.
Rubber-covered rolls or rollers in the draw-in mechanism of the displacing machine lead in particular increasingly to lapping due to adhesion proneness of the elastan filaments.
The use of teflon-coated draw-in rollers, or rolls or rollers coated with hard paper, ensures, conversely, satisfactory operation.
Because of the high extension and elasticity of the filaments, the speed between the delivery of the filament, the so-called production speed, and the speed of the preferably hard paper-coated draw-in rollers must be coordinated well with one another. As a rule an advance speeding-up of the draw-in rollers of 10% is sufficient with production speeds of less than 100 m/min. At higher speeds the advance speeding-up of the draw-in rolls or rollers comes with advantage to 20 to 50% more than the production speed of the elastan filaments.
Filament pile-up of the elastan filaments occurs mainly at the hand-over point of the filaments from the draw-in mechanism onto the oscillating special funnel draw-in. In order to prevent adhesion in the storage funnel, the supply of compressed air in the filament running direction directly at the funnel inlet has proved to be particularly suitable. Depending on production speed and throughput, it is often of advantage for the compressed air supply at the funnel inlet to be distributed over 2 points in some cases. In general small amounts of compressed air of between 1.2 to 1.5 bar are quite sufficient to achieve good passage of the filaments.
A further important role for an improved tape storage in the carton is also played by the funnel width of the oscillating inlayer to be used.
It was found that a relatively particularly loop-free tape storage of the elastan filaments is always obtained if the funnel width comes with titres of up to 10,000 dtex in particular to not more than 50 mm, preferably 30 mm and less.
In order to ensure a satisfactory storing of the coarse-titre elastan filaments in the carton, an additional transverse oscillation of the carton, offset 90xc2x0 relative to the filament running direction, has proved to be beneficial, as was described above.
By alternate restraining of the elastan tape with a tape holding-down device in the form of two rams, a significantly higher proportion of parallel storings of the elastan tape is obtained.
Cartons with the dimensions 600 mm lengthxc3x97400 m widthxc3x97500 mm height have provided to be particularly suitable carton sizes for the storing of the elastans. There may be stored in such cartons, for example, elastan filaments of the titre 10 000 dtex with 20 to 30 kg fabric weight, which corresponds to a filament line length of approx. 20 to 30 km.